0603s are easily solderable with an iron and an Optivisor. There's a knack to 0402s, but they're entirely manageable. Hot tweezers make the job far easier, but it's perfectly manageable with a decent iron and a steady hand. Smartphone repairers are now often dealing with 01005 parts, which are barely visible to the naked eye. As mrob suggests, working with SMDs is often easier than PTH if you know the proper techniques.
A lack of schematics is a problem, but that problem has existed for decades. The most common repairs are broken connectors and failed electrolytics, for which no schematics are required. Schematics for popular smartphones, tablets and laptops are readily available; ZXW make a superb interactive schematic package that massively simplifies the fault finding process.
I think it's very much swings and roundabouts. Some things are more difficult than they used to be, but the tools and information are far more accessible. There are thousands of excellent tutorials on YouTube demonstrating practically every aspect of electronics repair. Test equipment has become dirt cheap. Most components are readily available; for those that aren't, eBay's "spares or repair" listings are a treasure trove.
In my opinion, repair is less common simply because consumer electronics have become so cheap relative to the labor needed to repair them. The number of repairs that are economically viable has dwindled as prices have fallen. By the time something has failed, the odds are fairly good that it has been rendered obsolete.
The problem is that it's nearly impossible to get schematics for most devices, and I'm not even talking about legally since you'll have to do it illegally for virtually any device any how.
Many SMD components are not marked at all, which means that if some tiny SMD component gets fried you can't even know what it was for sure not to mention it's value without having another board to measure.
Not to mention that with 402 and 603 sized packages becoming more and more common goodluck soldering those at home even with professional kits, these are 0.4MM packages, sure 1608 and even 1005 are doable by a steady hand but anything smaller and you likely won't even be able to see the damage on the board.
And without schematics you can't really debug anything, you might be able to reverse some of the boards but anything beyond 2-3 layers is impossible to RE by hand without an x-ray scattering machine.
And then we get into active components and custom chips which are either impossible to get hold off without cannibalization or would cost you more to buy even in bulk on digikey or any other store than the devices you attempt to fix.
Sure a 2000$ Macbook is worth a 400$ fix, but a 50$ controller board doesn't.